In recent years, in order to improve high-speed performance of a radial motorcycle tire, the tread reinforcing belt changes its structure from the conventional two-cross-ply breaker whose cord angles are relatively large to a zero-degree band whose cord angle is almost zero degree with respect to the tire equator.
In comparison with such conventional two-cross-ply breaker, the zero-degree band can provide a larger circumferential restricting force for the tread portion to improve high-speed performance during straight running, and the axial bending rigidity of the tread portion becomes lower to improve the absorbability for disturbance from the road surface. As a result, shimmy of the vehicle body and handlebar vibrations during high speed straight running is effectively controlled to improve high-speed stability and the like. On the other hand, however, when compared with the two-cross-ply breaker, cornering performance has a tendency to deteriorate due to the lower axial bending rigidity.
It may be easily imagined that a zero-degree band and a two-cross-ply breaker are used in combination. In this case, the cornering performance may be improved, but the disturbance absorbability deteriorates. Thus, the disturbance absorbability and cornering performance are in an antinomic relationship.
It is therefore, an object of the present invention to provide a radial motorcycle tire, in which such antinomic requirements, disturbance absorbability and cornering performance are satisfied at the same time.